HanDBase, the award winning relational database, is available for Android devices.
This Plus edition is an Add-on. The HanDBase for Android client software itself is sold only through the Google Play market.

From your device, run the Google Play app and search for HanDBase.

After you've done that, or if you have already, you can then purchase this Plus Add-on which includes the following:

HanDBase Desktop Windows companion.

Two-way synchronization conduit.

The HanDBase Conduit for Windows enables you to Synchronize your databases between your Android device and Windows desktop versions of HanDBase. Now all changes to the same database, down to the record level, on either the handheld or desktop are merged together when you connect your device and synchronize!

System Requirements

HanDBase for Android running on an Android Device with OS 1.6 or newer.
10MB of Hard Drive space.
USB connection to Android phone or memory card slot to accept Android device's memory card or alternatively both desktop and Android device must both connect to the same Wifi Network for wireless syncing.